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ISSN (Online) : 2319 - 8753 ISSN (Print) : 2347 - 6710
International Journal of Innovative Research in Science, Engineering and Technology
Volume 3, Special Issue 3, March 2014
2014 International Conference on Innovations in Engineering and Technology (ICIET’14)
On 21st & 22nd March Organized by
K.L.N. College of Engineering and Technology, Madurai, Tamil Nadu, India
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M.R. Thansekhar and N. Balaji (Eds.): ICIET’14
Assessment on Ergonomics Risk during
Team Lifting
M.Harish Babu1, M.Uthayakumar
2, K.Murugabhoopathy
3
1M.Tech (Industrial safety Engineering), Kalasalingam University, Tamilnadu, India
2Head of the Department of Automobile Engg, Kalasalingam University, Tamilnadu,
India 3Senior Manager, Salem Steel Plant (SAIL), Tamilnadu, India
ABSTRACT— To ensure employee safety by
Ergonomics principles and knowledge of the human body,
this paper mainly addresses the issue of team lifting when
changing the job holders of Motorized Duplex Tong Crane
in a Hot Rolling Mill. This work also analyzes the
ergonomic risk factors by the tools such as Rapid Entire
Body Assessment tool (REBA) and Revised National
Institute of Occupational Safety and Health (NIOSH)
lifting equation. Ergonomics hazard is evaluated by
NIOSH hazard evaluation worksheet to minimize the
hazard level. Based on the analysis it is found that suitable
control measures can be provided for safe lifting.
KEYWORDS— NIOSH; Ergonomics; REBA; Hot
Rolling Mill.
I. INTRODUCTION Ergonomics is the science of improving employee
performance and well-being in relation to job tasks, equipment, and environment. It is a relentless pursuit and continuous effort to design the workplace for what people do well, and design against what people does not do well, thereby fitting the job to the person to enhance human performance. The desire to improve tools and working conditions is an innate human trait. The conceptual basis of ergonomics has existed for over 500 years. As a result of a surge in activities associated with increasing industrialization, the discipline began to formalize during the twentieth century. The word ergonomics was created in 1949 to define a growing area of research and engineering interest involving the interaction of people with industrial and military technology and demanding physical environments.
Criteria were developed that defined the limits of human capacity. Descriptive statistics outlined visual and auditory perception, mental workload limits were roughly defined, human reach and strength limits were cataloged, and initial work on physiological capacity defined cardio-
Pulmonary limits for exertion. Taken together, these laws of work defined the limits to human capability much like the specifications for a machine define its limits.
Ergonomic issues in the workplace can be summarized as awkward positions, excessive forces, and extreme frequencies of movement. These are the primary risk factors for the development of work-related musculoskeletal disorders [1] (WMSDs). Just like the fire triangle, in which three components - postures, forces, and frequencies can work together to turn small ergonomic issues into big problems and create an Ergonomics Fire Triangle. The same risk factors that contribute to WMSDs are also barriers to industrial performances. Repeatability of production operations is compromised when extreme postures are required, and recovery times from high level force applications increase the non-value-added content of work tasks. At a microelement level, the similar motions that contribute to ergonomic risk are the motions that rob operations of efficiency.
The Ergonomics Fire Triangle reminds us to focus job improvement efforts on the most critical ergonomic issues.
II. RELATED WORK
Work related low back disorders[1] (LBDs) due to
manual lifting tasks (MLTs) have long been recognized as
one of the main occupational disabling injury that affects
the quality of life of the Industrial people to understanding
the phenomena of LBDs and building classification that
could effectively distinguish between high risk and low
risk MLTs that contribute to LBDs. As of today, however,
the occupational exposure limits of different risk factors
causing LBDs as well as the guidelines preventing them
have not yet been fully proposed.
The purpose of this study was to investigate the effect
of an individual lifting capacity and stature on the
efficiency of team lifting[2] work. An experiment which
simulated a form-lifting task on a construction work site
Assessment on Ergonomics Risk during Team Lifting
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M.R. Thansekhar and N. Balaji (Eds.): ICIET’14
was performed. A two-man work team lifted a box from
knuckle height to shoulder height at a rate of 2 lifts per
minute. This study was to investigate the effect of
individual lifting capacity and stature on the efficiency of
team lifting work. It is concluded that the difference of
stature and the difference and the sum of individual lifting
capacities in a team affect team lifting efficiency and
capacity. It is recommended that the difference of stature
in team members should be minimized in a team lifting
work.
Work related musculoskeletal disorders (WRMDs)
are a leading cause of disability and workers
compensations. Rapid entire body assessment [3,4]
(REBA) was carried out to assess musculoskeletal
loads on workers due to their postures, repetition,
and force. Nordic musculoskeletal questionnaire
(NMQ) was also used to obtain prevalence of entire
body disorders.
III. DEFINITION OF PROBLEM
The objectives of this study are to conduct a risk
assessment during team lifting[2]. It is simple and careful
examination on what various of work could cause harm to
people, so that enough precautions should be taken and to
prevent harm. Employees have a right to be protected
from harm caused by a failure to take reasonable control
measures. Accidents and ill health can affect lives and
business. Assess the risks in workplace so that it provides
suitable plan to control the risks.
IV. FIELD STUDY AND DATA COLLECTION
The study has been carried out in Hot Rolling Mill
section Workers while carrying and lifting the job holders
are examined carefully by Applying a two method
REBA[3,4] and Revised NIOSH Lifting equation[5]. The
objective of the preliminary work was therefore to
highlight the dominant risks within the chosen steel plant.
This holds true as the specified plant had thousands of
workers present working within hundreds of different
workstations and tasks. Medicinal records were for that
reason used to gain a perceptive insight as to where to
concentrate first in order to conduct a relevant ergonomic
risk assessment. The work background, job requirements
and diagnostic criteria play a vital role in identifying the
prevalence of any Musculoskeletal disorders MSDs[6]
and cyclic maintenance work, such as that found on an
assembly line in an steel plant[6], is known to be a high
risk for MSDs . An observation period of the assembly
tasks within the lines was then conducted to identify
problem areas and facilitate in the quantification and
categorization of the risks. The manual assembly area was
selected as this had the manual materials handling and
placed the greatest demands on the workers. Once specific
lines and tasks had been identified, information that is
more detailed was required with risk assessment tools.
Hence, prioritization of the lines occurred and high-risk
tasks were identified for further scrutiny in the laboratory.
The following manuscript refers to the initial phase of the
assessment, which includes the methodology followed to
identify risk and narrow the focus, including the details
and results obtained through the aforementioned process.
A. Rapid Entire Body Assessment method using
ErgoFellow (Version – 2.0) software
The Rapid Entire Body Assessment (REBA) tool[3,4]
for application in the health care and other service
industries. Here posture, force, movement or action,
repetition and coupling are assessed. It means to assess
position for the risk of WRMSDs. The tool considers
critical areas of a job and for each task; it assesses the
position factors (Refer with Fig - 1,2,3,4,5) by assigning a
score to each region. The data obtained through
assessment of the task is then entered which gives a
REBA score for each task that indicates the level of risk
and urgency with which action should be taken. Various
criteria can also be used to choose postures to analyze and
the use of time sampling can be utilized. Using
ErgoFellow (Version-2.0) software to obtain perfect
result.
Fig .1 Select Neck, Trunk, Leg Positions
Fig .2 Select Load Range
Assessment on Ergonomics Risk during Team Lifting
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M.R. Thansekhar and N. Balaji (Eds.): ICIET’14
Fig .3 Select Upper arm, Lower arm, Wrist Positions
Fig .4 Select Coupling factor
Fig .5 Select Activity
Fig .6 Result
Comments-
REBA Total score is 8.So Risk level is High (Refer
with Fig-6) some modification like engineering
improvements required during team lifting.
B. Revised NIOSH lifting equation
The objective of this study is to evaluate the internal
validity of the NIOSH lifting equation[5] with the results
of psychophysical and biomechanical data obtained from
laboratory studies involving two man (Team lifting) tasks
performed.
a) Evaluate of the differences between the
Recommended Weight Limit (RWL) and Maximum
Acceptable Weight of Lift (MAWL) obtained from this
study;
b) Estimation of the Lifting Index (LI) of the different
task conditions studied;
c) Investigation of the form of the asymmetric
multiplier in the revised NIOSH equation and its
applicability to the tasks discussed in this study;
RWL = LC × HM × VM × DM × AM × FM × CM LC - Load Constant; HM - Horizontal Multiplier; VM -
Vertical Multiplier; DM - Distance Multiplier; AM -
Asymmetric Multiplier; FM - Frequency Multiplier; CM -
Coupling Multiplier
For Single man lifting -LI = Load Weight / RWL
For Two man Lifting ( RWL = 0.90 × RWL Calculated)
LI PERSON-1 = ( ½ Actual Weight)/(0.90 × RWL PERSON-1)
LI PERSON-2 = ( ½ Actual Weight)/(0.90 × RWL PERSON-2)
Assessment on Ergonomics Risk during Team Lifting
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Fig .7 Worksheet for Person-1
Fig .8 Worksheet for Person-2
Comments-
Lifting pattern is continuous over 35 minutes work
session. Lifting index are more than 1(Refer with Fig – 7,
8). Eliminate the manual lifting method of the job and
appropriate lifting method and redesign of working
method is required.
C.NIOSH Hazard Evaluation worksheet
Risk factors (General & Specific) involved in the
process were checked by NIOSH Hazard evaluation
worksheet. Potential risk involved in each activity was
assessed by NIOSH work sheet and found to be more
“Yes” responses. This is the indicative of conditions that
pose a risk of developing low back pain, the larger the
percentage of “Yes” responses, the greater the risk(Refer
with Table – 1). Based on the results, focus was given to
reduce the risk factors
TABLE.1 NIOSH Hazard Evaluation worksheet
RISK FACTORS
YES
NO
GENERAL
1.1 Does the load handled
exceed 50 lbs.?
YES
1.2 Is the object difficult to
bring close to the body
because of its size, bulk, or
shape?
YES
1.3 Is the load hard to handle
because it lacks handles or cut
outs for handles, or does it have
slippery surfaces or pointed
edges?
YES
1.4 Is the footing unsafe? For
example, are the floors
slippery, inclined, or uneven?
NO
1.5 Does the task require
fast movement, such as
throwing, fluctuation, or rapid
walking?
YES
1.6 Does the task require
stressful body postures such as
stooping to the floor, twisting,
reaching overhead, or excessive
tangential bending?
YES
1.7 Is most of the load handled
by only one hand, arm, or
shoulder?
NO
1.8 Does the task require
working in environmental
hazards, such as extreme
temperatures, noise, vibration,
lighting, or airborne
contamination?
NO
1.9 Does the task require
working in a confined area? NO
SPECIFIC
2.1 Does The Lifting Frequency
Exceed Five Lifts Per Minute
(Lpm)?
NO
2.2 Do carries last longer than
one minute?
YES
2.3 Does the vertical lifting
distance exceed three feet?
NO
2.4 Do tasks, which require
large sustained pushing or
pulling forces, exceed 30
seconds duration?
YES
2.5 Do extended reach static
holding tasks exceed one
minute?
YES
Total
8
6
Assessment on Ergonomics Risk during Team Lifting
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M.R. Thansekhar and N. Balaji (Eds.): ICIET’14
V. REMEDIAL ACTIONS
Based on the analysis eliminate the team lifting method and using some alternate lifting method.
1) Use mechanical handling aids like tools, Hoists,
Manipulators, counter balanced lifters, Pallet lifts, Tilt
lifts, Stackers, Forklifts.
2) Eliminate load carrying and using
Trolleys,Conveyors.
3) Match the workstation height with Trolleys.
4) Examine the possibility level of using team lifting
for less frequent operation.
5) Consider workplace height.
6) Floor suface should be clean.Remove loose
materials from work place.
7) Consider work area layout.
8) Reduce need for operatives to bent while lifting.
9) Reduce need for operatives to reach over head and
shoulder height.
10) Ensure loads are positioned conveniently close to
the operative to avoid excessive reaching.
11) Raise pallet loads up from the ground, use pallet
lifts, tilt lifts or height flexible tables and trolleys.
Consider workplace, trolley and equipment height and
layout. Adjustability to suit a variety of individuals is
preferable.
12) Self levelling pallet lifts and tables can be used to
control lifting height to below shoulder height for stacking
operations, inspect shelf heights. Organise operations such
that high and low level handling is only carried out for
infrequent and / or lighter weight operations.
13) Ensure the preponderance of loads, tools and work
components are positioned in front of the operative.
Locate the target point of a load far enough away from the
operative to increase the likelihood of operatives moving
their feet. Use conveyors or trolleys to transfer loads, use
ball bearing conveyors to move loads in different
directions. Initiate operatives to move their feet and
maintain good trunk posture.
VI. CONCLUSION AND FUTURE ENHANCEMENT
Risk factors are identified in a (Hot Rolling Mill) steel
plant, which needed ergonomic Assessment. The purpose
of this work was to examine lifting. Poor posture and
improper lifting movements can lead to local mechanical
stress on the physique, ligaments and joint. This results
problem with neck, back, shoulder and wrist. These
problems can be avoided by executing this work. This
lifting method can be enhanced by safe alternate lifting
methods as a future work.
ACKNOWLEDGMENT
This work fully supported by management of Salem
Steel Plant (SAIL). They granted us permission to carry
out this work successfully.
REFERENCES
[1]. Jozef Zurada, “Classifying the risk of work related low back
disorders due to manual material handling tasks”, Expert Systems
with Applications (2012), vol.39, pp.11125–11134.
[2]. K.S. Lee, J.H. Lee, “A study of efficiency of two man lifting
work”, International Journal of Industrial Ergonomics (2001), vol.27, pp.197–202.
[3]. Syyed Ali Moussavi – Najarkola, Ramazan Mirzaei “Assessment of Musculoskeletal Loads of Electric Factory Workers by Rapid
Entire Body Assessment” Research Article - Health Scope - 2012
August; 1(2): 71-79.Published online 2012 August 7 | DO I: 10.5812/jhs.6654.
[4]. Hignett, S and McAtamney, L., 2000, Rapid Entire Body Assessment (REBA), Applied Ergonomics, 31, 201-205.
[5]. Thomas R. Water , Vern Putz-Anderson, Arun Garg & Lawrence J. Fine “Revised NIOSH equation for the design and evaluation of
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[6]. E Habibi, M Fereidan, A Molla aghababai, S Pourabdian
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